1. Field of the Invention
The present invention relates to a parking brake apparatus, in more detail, a parking brake apparatus that can ensure the parking condition of a vehicle without transmitting operational force of a driver through a mechanical power transmission process.
2. Description of Related Art
Automated transmissions, such as automatic transmission or automated manual transmission, in the related art, generally have used a mechanism that is configured such that a parking gear fitted on an output shaft connected to driving wheels of a vehicle is fixed by a parking sprag, a parking cam that is operated through a cable transmitting operational force of a driver actuates the parking sprag to change the fixed position of the parking gear, thereby changing the parking condition.
On the other hand, recently, a mechanism that mounts a parking brake actuator, which makes it possible to change the fixed position of a parking gear by hydraulic pressure and electricity, in a transmission is used, such that it is possible to change the parking condition without directly and mechanically transmitting operational force of a driver through a cable.
The parking brake actuator generally changes the fixed position of the parking gear by motion of a piston rod of a piston that reciprocates straight, in which the motion in one direction of the straight motion direction of the piston is made by hydraulic pressure and the motion in the opposite direction is made by the elasticity of a spring. Therefore, the actuator is provided with a configuration of moving the piston using the hydraulic pressure and a configuration of applying the elasticity of the spring in to opposite direction, such that the structure is complicated and the size of the package increases, and accordingly, it is difficult to mount the parking brake actuator in a transmission.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.